Primer composition



Patented Feb. 19, 1946 COWOSITION George U. Grafi, Washington, C.

No Drag. Application February 27, 1939,

Serial No. 258,724

4 Claims. (Cl. 52-2) (Granted under the act of March 3, 1883, as

amended April 30, 1928; 370 0. G. 757) This invention relates to a primer composition, and has for an object to provide a primer composition intended for use as a projectile or bomb fuse initiator, particularly in connection with lead azide, but also utilizable in initiating ignition of pyrotechnics or other devices.

A further object of this invention is to provide a primer composition for the above uses having improved characteristics, particularly stability against heat and moisture.

With the above and other objects, the combination consists in the composition and combination as will be hereinafter more fully described.

The detonation of lead azide may be brought about by the application of heat as well as by violent shock, and the priming mixture of this invention is intended to generate heat sufficient to cause the detonation of the lead azide. It also has the property of having keeping qualities comparable to lead azide.

The preferred composition of the primer mixture of this invention gives a drop test of 2% inches with a 4 ounce weight when loaded into a standard priming cup. The preferred composition may be varied within certain limits and in some cases manganese dioxide may be substituted for part of the lead peroxide, according to the following table, which, when used under identical conditions, shows the sensitivities obtained from mixtures in which the proportions of the ingredients were varied:

Manganese Lead Calcium Drop dioxide peroxide Bilicide Zkmmm mph: test Inches 45 20 26 10 2% 45 25 20 i 4 46 80 15 10 4% 45 1B 80 10 4 45 16 25 i5 6 60 20 26 6 4 60 .19 23 8 8 10 86 ill 26 10 8 20 25 2o 25 10 Preferred mixture.

In the last two mixtures of the above table manganese dioxide is substituted for part of the lead peroxide, because it has moisture-resistant properties similar to lead peroxide, and at the same time has a higher oxygen content than lead peroxide, thus providing a mixture in which a more complete combustion is obtained. However, as shown by the above table, a satisfactory combustion is obtained with the preferred mixture heading the table, at a lesser drop.

Lead azide loaded in a detonator is comparatively insensitive to shock, for by experiment it was found that a 2 ounce weight with a stab type firing pin gave a drop test of greater than 22 inches on a detonator loaded with lead azide, while a similar detonator loaded with mercury fulminate gave a drop test of 8 inches.

It is to be understood that the proportions specified for the several ingredients represent the preferred percentages for each combination, but strict adherence thereto is not essential, as good results are obtained. even when they are varied within considerable limits.

The invention described herein may be manufactured and/or used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

Having thus set forth and disclosed the nature of this invention, what is claimed is:

1. A primer composition for initiating the detonation of lead azide comprising substantially parts of lead peroxide, 15 to 30 parts of calcium silicide, 30 to 15 parts of zirconium, and 10 to 15 parts of sulphur.

2. A primer composition for initiating the detonation of lead azide comprising 45 parts of lead peroxide, 20 parts of calcium silicide, 25 parts of zirconium, and 10 parts of sulphur.

3. A primer composition for initiating the detonation of lead azide comprising parts of lead peroxide, 19 to 20 parts of calcium silicide, 25 to 23 parts of zirconium, and 5 to 8 parts of sulphur.

4. A primer composition for initiating the detonation of lead azide comprising 10 to 20 parts of manganese dioxide, 35 to 25 parts of lead peroxide, 20 parts of calcium suicide, 25 parts of zirconium, and 10 parts of sulphur.

GEORGE U. GRAFF. 

